The effects of cyclophosphamide on delayed hypersensitivity in rats

Pretreatment of Tuck Wistar rats with cyclophosphamide (100 mg kg-1) intraperitoneally prevents the development of adjuvant-induced arthritis, experimental allergic encephalomyelitis and the delayed skin reactions after ovalbumin and Freund's incomplete adjuvant. The resistance of these rats to these stimuli is similar to that found in untreated NR Wistar rats which are resistant to dextran. However, cyclophosphamide suppresses the responses of Tuck Wistar rats to collagen-induced arthritis and sheep red blood cell agglutination, stimuli to which untreated NR Wistar rats respond. Nevertheless, the reactions of Tuck animals to the purified protein derivative of M. tuberculosis, the skin sensitisation to oxazolone, and the development of the delayed reaction after ovalbumin and Freund's complete adjuvant remain unchanged after cyclophosphamide pretreatment. The results indicate the possible existence of two separate types of delayed hypersensitivity reactions.